With the popularity of computers and the advance of networking technology, the Internet touches every corner of our daily life. The development of the Internet not only brings us a convenience, but also brings us a variety of challenges as well. Some malicious users may use robot programs to massively occupy Internet resources, such as sending spam mail or a massive attack. To avoid such malicious behaviors, a server is usually configured to have a program tool that can automatically identify a user as a malicious user or a goodwill user to reduce a risk of malicious attack on the server.
A diagram authentication code is a program tool that is used for indentifying an Internet user as a goodwill user or a malicious user. The diagram authentication code is a diagram including words by which a user is requested to answer. Once a user can correctly answer, he/she will be regarded as a goodwill user and will be allowed to proceed to the next operations.
Regarding the conventional authentication code generating system, it generally pre-generates an authentication library including enormous authentication code diagrams. For every submission of authentication request, the system will pick up one authentication code diagram from the authentication library. However, there is only one diagram displaying mode for displaying the conventional authentication code by which it only displays words and a single-color background. Recently, related anti-crack mechanisms have been added, such as adding of background or adding of noise lines. However, some mechanisms may cause bad user experience because, for example, they add too many improper noise lines.
In addition, the form of the conventional authentication code is non-adjustable or the adjustment is not flexible. Accordingly, the form cannot be effectively adjusted timely during a malicious attack. With the increment of on-lining operations, the conventional authentication code is relatively easily cracked. This causes risks and defects for network security.